The invention relates generally to a method and apparatus for forming sheet material, such as sheet metal, into an article having a desired configuration and cross-sectional shape. More particularly, the invention relates to methods and apparatus for roll-forming a sweep or curvature into such article.
In conventional cold roll-forming methods and apparatus, a flat strip of sheet material, such as sheet metal or the like, is longitudinally passed between a series of corresponding forming rolls that progressively deform the sheet material into a desired configuration and cross-sectional shape. Although such methods and apparatus have become well-developed over the years, and have proved to be quite successful and advantageous in cold-forming a wide variety of articles and products, they have previously been very limited in their capability to form article configurations having a longitudinal sweep or curvature. Such methods and apparatus have been especially incapable of sweep-forming curved configurations from various high-strength, light weight materials, such as high-strength, low alloy (HSLA) steel. Such materials are very desirable for the fabrication of products such as automotive bumpers, for example. Because of the difficulty or infeasibility of sweep-forming such materials, products that require a sweep or curvature have previously been formed by other conventional techniques, such as by stamping, stretch-forming, or extruding and have thus been expensive and difficult to accomplish efficiently.
According to the present invention, sweep-forming apparatus, which is preferably located at the end of a roll-forming line, generally includes a base assembly and one or more forming stations serially-disposed in a longitudinal direction and adapted to introduce a sweep or curvature into a previously-formed elongated article. At least one of such forming stations preferably includes transversely off-set forming rolls for permanently deforming the elongated article in a transverse direction and apparatus for substantially constraining substantially all of the lateral and transverse surfaces of the previously-formed article during the introduction of a sweep therein without introducing undesirable wrinkles, folds or other undesirable deformations into the article. Preferably, the transverse position of each forming station is adjustable in order to progressively displace successive forming stations farther in the transverse direction from the base assembly and thereby accommodate various degrees of sweep in varying applications.
Additional advantages and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.